The U.S. Environmental Protection Agency (EPA) has set National Ambient Air Quality Standards (NAAQS) for six common air pollutants, also called “criteria” pollutants. The criteria pollutants are carbon monoxide, nitrogen dioxide, ozone, lead, particulate matter and sulfur dioxide. NAAQS are often referred to as federal health standards for outdoor air.
The Clean Air Act, which was passed in 1970 and last amended in 1990, requires the EPA to set NAAQS for pollutants that cause adverse effects to public health and the environment. The Clean Air Act established primary and secondary air quality standards. Primary standards protect public health, including the health of “sensitive” populations such as asthmatics, children, and the elderly. The primary standard is often referred to as the health standard. Secondary standards protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings. Standards are reviewed periodically to ensure that they include the most recent scientific information.
Non-attainment areas are regions within the country where the concentration of one or more criteria pollutants exceeds the level set as the federal air quality standards. Once the EPA announces that an area does not meet the health standard, the State works with businesses, local governments, and the public to reduce the emissions from sources contributing to the non-attainment status of the area.